Safety devices for inclined elevators



y 1959 w. STELZER 2,886,136 SAFETY DEVICES FOR INCLINED ELEVATORS Filed July 5, 1955 2 Sheets-Sheet 1 LW /1-2 VA A 3 A\\\\\\1\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\s I V EN TOR.

May 12, 1959 w. $TELZE\R' I 2,836,136

SAFETY DEVICES FOR INCLINED ELEVATORS Filed' July 5, '1955 2 Sheets-Sheet 2 I N VEN TOR.

2,886,136 SAFETY DEVICES FOR IN CLINED ELEVATORS William Stelzer, Summit, NJ.

Application July 5, 1955, Serial No. 520,050 4 Claims. Cl. 187-13) The invention relates to safety devices for inclined elevators and more particularly to devices for inclined elevators to automatically stop the elevator car when it encounters a certain increased resistance in the direction of upward travel, or to prevent rapid descent of the reaks, or is disconnected.

' The object of the invention is to provide a simple balance mechanism to balance the weight of the loaded car against the pulling force which causes the car to ascend on the inclined plane, Where an increase in the mechanism, which is used to close an electric control circuit or operate other control means to reduce or shut off the power of the elevator to arrest the car.

Another object is to use the same balance mechanism in combination with brake means to engage such brake means in case of breakage of the towing element lifting the load carrying car to arrest the latter.

A further object is to yieldingly bias the balance mechanism to remain in a normal position so that a certain excess resistance above the normal resistance has to be encountered before the power is reduced.

-A still further object is to include means for automatically severing the tow element from the car in case of a severe resistance to the ascent of the car.

Other objects and advantages of this invention will be apparent from the following description considered in connection with the accompanying drawings submitted for the purpose of illustration and not to define the scope of the invention, reference being had for that purpose to the subjoined claims. In the drawings, wherein similar reference characters refer to similar parts throughoutthe several views:

Fig. 1 is a cross-sectional side elevation of the platform and track of an inclined elevator incorporating the 1 invention;

Fig. 2, a section taken on lines 2-2 of Fig. 1, the section being shown as though the track were level;

Fig. 3, a section taken on lines 3-3 of Fig. 1, this section'also being shown as though the track were projected on a level plane;

Fig.4, a diagram of the hydraulic and electric circuits of the elevator;

Fig. 5, a diagram of a wheel suspension on the inclined track, illustrating the principle of the invention; and l i 6, a diagram showing a modification of the balance mechanism to illustrate how the principle of the inventionis applied to an inclined elevator in which the motoris carried in the elevator car.

'Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrange.-

ment of elements illustrated in the accompanying drawings, since the inventionis capable of other embodiments levator car incase the cable or other hoisting line they are not shown.

and of being practised or carried out in various ways.

Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not limitation.

The improved elevator comprises an elevator car 1 having wheels 2 running on an inclined runway or track 3 which may be secured onto or run along a stairway, not shown. At one side the track has a channel-shaped guide 4 to guide the right front and rear wheels 2 to thereby keep the car lined up with the track. The wheels 2 revolve on pins 6 of arms 7 secured to shafts 8 revolvably supported by brackets 9, 10 and 10' extending from the body or frame 11 of car 1, body 11 encasing the wheels and balance mechanism and serving as a plat form on which the operator stands. The platform may be equipped with the usual handrails or seating means, but since these form no part of the present invention Shafts 8 carry levers 12 fixed at right angles with cranks 7 and linked together by a connecting rod 14 having slotted ends provided with pivot pins 15. The slotted upper or front end of connecting rod 14 is extended to pivotally support a pawl 16 by means ofa pin 17. The pawl is engaged by a hook 18 secured to the end of a tow line 19, which may be a belt, chain, or cable. The tail end of pawl 16 abuts against the edge 13 of body 11 where a certain movement of connecting rod 14 upwardly along track 3 causes pawl 16 to slip olf edge 13 to release tow line 19, Arms 7 are parallel with and levers 12 of the elevator car urges the latter to move towards track 3 and the towing force exerted through tow line 19 and connecting rod 14 urges the car to move away from track 3. By selecting the right lengths of arms 7 and levers 12 for a given incline of the track, the forces are in balance and the balance mechanism is in the normal position shown. Fig. 5 shows a force diagram for an incline of 30 degrees. Where a is the angle of the incline, W the weight of the car acting on the axis of the wheel, Q the force perpendicular to track 3, and P the resultant downward thrust, then P=W sin a. Designating the length of arm 7 with b, F being the force exerted through the tow line 19, without taking friction into account, to produce a balance the length of levers 12 should be equal to b cos a. In order to provide 1 a certain stability so that the car does not bounce unnecessarily in a direction perpendicular to the track, I provide a leaf spring 20 engaging an abutment 21 of rod 14 to bias the latter towards the normal position when yieldingto force F. Spring 20 is secured to body 11 and made. adjustable by a screw 22 and nut 23. A stop 24 extending from body 11 serves to arrest the spring when the connecting rod 14 is in the normal position. Thus spring 20 resists movement of car 1 from the normal position away from track 3. To provide an initial resistance to movement of the car towards the track, levers 12 are made somewhat longer so that abutment 21 normally presses against spring 20. The latter has sufiicient strength so that it does not yield to a normal increase in force, such as is caused by friction. The spring should yield, however, if force F is sulficiently increased out of proportion to the load, as would occur if an obstacle were placed in the path of the car. The purpose of the yielding movement of connecting rod tor fshownin Fig. 4, which will be described later. upward. movement of rod 14 will also cause the release of the tow line when the end of pawl 16 slips over edge e pose, it is not necessary that both be used except in special cases. Where the deenergizationof .the motor or stoppage of car 1 by switchf27 is too slow, the release mechanism 16+-18 may .addgreater safety than switch 27." If the release mechanism Iii-18 'is..not us'ed,a stop 29 extending from-rod 14 abuts against. upper lever 12 to prevent damage to switch 27. Reductionof force F out of proportion with load W causes the car. to. move towards'the track and engage brakes whichconsist of shoes 31 and 32 secured to body 11 and having tapered friction surfaces fittinginto V-shaped grooves. 33 and 34 cut longitudinally in track 3. The taper of the grooves and mating shoes is such that if line 19 is released and the total weight of the car is supported by brake shoes 31 and 32, the braking action is sutficient to stop the car. In the position described, connecting rod 14 has moved downwardly along the track to open a normally closed switch 35, so that the power isshut ofi.

Referring now to the diagram in Fig. 4, the car 1 is lifted by the force of a hydraulic motor 40 consisting of a.

cylinder 41 and plunger 42 carrying a sheave 43 to place the tow line 19 in tension. The power is supplied by an electric motor 44 driving. a pump 45' transmitting fluid under pressure through a check valve 46 to cylinder 41. A normally open relief valve 47 is closed by the force of asolenoid' 48 to place the hydraulic fluid in line 49 under pressure when pump 45 is running. The latter has its intake from asump or reservoir 50, into which a line 51 leads from relief valve 47. A throttle valve 52 in a line 53 intermediate cylinder 41 and sump 50 is' normally closed and operated by a solenoid 54, which, when opening throttle valve 52, permits the elevator to descend by its own weightv and without pump 45 running. The car is provided with a push button 56 for down travel and a push button 57 for upward travel. 58 are trolleys or brushes and 59 fixed trolley wires or bars. A'bush button 61 at the lower station and another push button 62 atthe upper station permit calling- All push buttons are normally open and.

spring 69. Closing pushbutton switches 57 or 62, be-.

side's energizing solenoid 48, also energizes a relay 70 to close the circuit of electric motor 44 from line 71.

In the modification diagrammatically illustrated in v 6 'the car 88 running on track 81 contains a motor whose J shaft 82 carries a drum 83 onto which the tow line 84' is wound. 'The latter has a fixed end at the upper end of the track. The diagram shows how the towing force is transmitted to connecting rod 85 which connects levers 12'; For the purpose a wheel 86 revolubly supported by a rod 85' serves as a sheave for the tow line 84 so that the towingforce is transmitted to rod 85 substantially as force F to rod 14 in Fig. 1, and the result is accordingly the same. While the tow line cannot be released, the switches 27 and 35 can be used, and the means to bias the connecting rod into a normal position .can be identical as already shown and described.

Describing now the operation of the construction shown in'Figs. 1-4, it should be pointed out that whether the elevator car is empty or not, the linkage is always, bal- Y anced, even during acceleration except if the friction of other resistance become excessive. If car .1 is standing'sftill',,'line .49 is under pressure from the welght of car 1 and plunger 42. The empty car does not have suf-' 44 to drive pump 45 which transmits fluid to cylinder 41 to cause the elevator to ascend until the push button is released or end switch 64 opened, when the motor is again deenergized. For the descent, if push button 56 or 61 is closed, the pump remains inoperative but solenoid 54 is energized to open throttle valve 52 so that hydraulic fluid from cylinder 41 can flow through line 53 into the sump or reservoir 50 whereby the elevator descends until the push putton is released or end switch 65 opened.

If during the ascent of the car the equilibrium of the linkage is disturbed, as for instance if something is caught accidentally between a part of the carrier and a tread of the stairway (which is easily possible in preseat-day inclined elevators provided with chairs for invalids), force F is greatly increased without a proportional increase in the vertical force component W, causing body 11 to move away from track 3 in a direction. perpendicular to track 3 with a relative movement of. connecting rod 14 in the direction of pull of tow line 19. This movement opens switch 27 and breaks the circuit to vdeenergize solenoid 48 so that valve 47 is opened.

and motor 45) stops. The opening of switch 27 may occur before operation of the release mechanism 16-18, or pawl 16. may be of such length that an additional increased force F is required to release line 19; Ifthe release mechanism 16-48 is used, switch 27 could be:

dispensed with, then after release of line 19 during an accident, body 11 would drop onto track 3 to cause en gagement of brake shoes 31 and 32 in grooves 33 and.

34 to stop the car. At the same time the relative down ward movement of rod 14 along track 3 would cause- 1. In a power operated inclined elevator having a car including a load carrying platform adapted to run on an inclined track, in combination, towing means in tension parallel with said track to tow said car on said track, a lever mechanism including an arm parallel with said track and pivoted at one end to turn about a horizontal axis fixed in relation to said platform, said arm carrying at the other and lower end a wheel in contact with said track, a lever perpendicular to said track and fixed in relation to said arm to pivot about said axis with the:

free end pointing towards said track, means to transmit the tension in said towing means to said free end of said lever, said lever and arm being so proportioned that the tension in said towing means is sufiicient tolift saidplat-form, away from said track in a direction'appro'ximately perpendicular to said track, resilient means toi resist the movement of said platform beyond a normal: operating position which is a short distance above said track; and means responsive to the movement ofv said platform away from said normal operating position to shut off the power of said elevator to thereby stop said car.

2. In a power operated inclined elevator having a car with a load carrying platform provided with wheels running on an inclined track, in combination, towing means in tension parallel with said track to tow said car on said track, a lever mechanism comprising a pair of. spaced transverse horizontal shafts whose axes are fixed in relation to said platform, a pair of arms parallel with said track when in a normal position and secured toeach of said shafts to pivot about the axis of said shaft,

each armcarrying at its lower free end one of said wheels in. contact with said. track, a lever perpendicularto said;- track and extending from each of said shafts towards; said track, a connecting rod pivotally connecting thev ends of said levers so that when said arms are rotated about said axes all points of said car move at equal velocity towards or away from said track, means to transmit the tension of said towing means to said connecting rod, whereby the tension in said towing means urges to lift said car away from said track in a direction perpendicular to said track, resilient means to bias said platform to yieldingly remain in a normal operating position raised a short distance above said track, and means responsive to the movement produced in lifting said car away from said track above said normal operating position to shut off the power of said elevator to thereby stop said car.

3. In a power operated inclined elevator having a car, the latter including a load carrying platform supported by wheels running on an inclined track, a lever mechanism pivotally connected to said platform and having bearing supports for said wheels movable relative to said platform in a direction approximately perpendicular to said track, towing means in tension parallel with said track to tow said car on said track, said towing means being connected to said lever mechanism so that the tension in said towing means tends to lift said platform away from said track in a path that is approximately perpendicular to said track when said wheels are considered as being at rest, said lever mechanism being so proportioned that the tension in said towing means required to tow said car is only slightly greater than necessary to lift said platform from said track, a friction element secured to said platform to engage said track when the tension in said towing means yields to the gravitational force of said platform, and means responsive to the movement of said platform away from a raised posi- 6 tion to disconnect the power of said elevator to stop said car.

4. In a power operated inclined elevator having a car, the latter comprising a load carrying platform and wheels, the axes of said wheels being movable relative to said platform in a direction perpendicular to said track, a friction element secured to said platform positioned for braking engagement with said track when. said platform rests on said track, towing means in tension parallel with said track to tow said car on said track, a lever mechanism engaged by said towing means to lift said platform from said track to rest on said wheels, said lever mechanism being so proportioned that the towing force required to tow said car is suflicient to lift said platform from said track, resilient means to yieldingly resist the lifting movement of said platform beyond a normal position, and means responsive to the movement of said platform above said normal position to disconnect said towing means from said lever mechanism so that said platform is released to come to rest on said track and is stopped thereby.

References Cited in the file of this patent UNITED STATES PATENTS 1,219,748 Klansnic Mar. 20, 1917 1,462,741 Crow July 24, 1923 1,513,296 Thorne Oct. 28, 1924 2,674,347 Thompson Apr. 6, 1954 2,719,607 Scott Oct. 4, 1955 

